The present invention relates to a method for signaling a fault of at least one subscriber line to be monitored to a central facility as well as to a monitoring system for monitoring such a subscriber line.
The acceptance of public telecommunications networks among the customers essentially depends on their reliability of operation and performance. Therefore, a major task of the network operators is to monitor established connections or connections to be established within these telecommunications networks and, if necessary, to perform a fault diagnosis.
One possibility of monitoring ISDN telecommunications networks is to measure and log ISDN basic accesses at the S0 interface at the telephone subscriber end (see, for example, the operating instructions of the ISDN S0 basic access measuring and testing device Pegasus from the Festo Didactic KG company, Esslingen, as of 02/95; page 85).
German Patent DE 197 29072 describes a method for measuring or logging an ISDN basic access which can also be executed independently of the telephone subscriber to be monitored. This is achieved by opening the UK0 interface at a point of the connection line that is convenient for measurement or logging. In the opened UK0 interface, the line signals arc converted into IOM signals, and the IOM signals are in turn converted into S0 frames. Consequently, all data of the tapped S0 interface are available to already existing S0 measuring devices at the point where the connection line is opened.